1. 05 1月, 2011 1 次提交
    • Y
      x86: Fix APIC ID sizing bug on larger systems, clean up MAX_APICS confusion · cb2ded37
      Yinghai Lu 提交于
      Found one x2apic pre-enabled system, x2apic_mode suddenly get
      corrupted after register some cpus, when compiled
      CONFIG_NR_CPUS=255 instead of 512.
      
      It turns out that generic_processor_info() ==> phyid_set(apicid,
      phys_cpu_present_map) causes the problem.
      
      phys_cpu_present_map is sized by MAX_APICS bits, and pre-enabled
      system some cpus have an apic id > 255.
      
      The variable after phys_cpu_present_map may get corrupted
      silently:
      
       ffffffff828e8420 B phys_cpu_present_map
       ffffffff828e8440 B apic_verbosity
       ffffffff828e8444 B local_apic_timer_c2_ok
       ffffffff828e8448 B disable_apic
       ffffffff828e844c B x2apic_mode
       ffffffff828e8450 B x2apic_disabled
       ffffffff828e8454 B num_processors
       ...
      
      Actually phys_cpu_present_map is referenced via apic id, instead
      index. We should use MAX_LOCAL_APIC instead MAX_APICS.
      
      For 64-bit it will be 32768 in all cases. BSS will increase by 4k bytes
      on 64-bit:
      
      	text		data		bss		dec		filename
      	21696943	4193748		12787712	38678403	vmlinux.before
      	21696943	4193748		12791808	38682499	vmlinux.after
      
      No change on 32bit.
      
      Finally we can remove MAX_APCIS that was rather confusing.
      Signed-off-by: NYinghai Lu <yinghai@kernel.org>
      Cc: H. Peter Anvin <hpa@linux.intel.com>
      Cc: "Eric W. Biederman" <ebiederm@xmission.com>
      LKML-Reference: <4D23BD9C.3070102@kernel.org>
      Signed-off-by: NIngo Molnar <mingo@elte.hu>
      cb2ded37
  2. 04 1月, 2011 1 次提交
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